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HAL_PX4: fixed RCInput race condition 

the number of channels could be zero with thread switch at the wrong
time
This commit is contained in:
Andrew Tridgell 2013-12-31 22:24:55 +11:00
parent 9df5887aab
commit 89676be825
2 changed files with 20 additions and 7 deletions
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23
libraries/AP_HAL_PX4/RCInput.cpp
View File

@ -17,11 +17,15 @@ void PX4RCInput::init(void* unused)
hal.scheduler->panic("Unable to subscribe to input_rc");
}
clear_overrides();
pthread_mutex_init(&rcin_mutex, NULL);
}
uint8_t PX4RCInput::valid_channels()
{
return _rcin.timestamp != _last_read || _override_valid;
pthread_mutex_lock(&rcin_mutex);
bool valid = _rcin.timestamp != _last_read || _override_valid;
pthread_mutex_unlock(&rcin_mutex);
return valid;
}
uint16_t PX4RCInput::read(uint8_t ch)
@ -29,15 +33,21 @@ uint16_t PX4RCInput::read(uint8_t ch)
if (ch >= RC_INPUT_MAX_CHANNELS) {
return 0;
}
pthread_mutex_lock(&rcin_mutex);
_last_read = _rcin.timestamp;
_override_valid = false;
if (_override[ch]) {
return _override[ch];
uint16_t v = _override[ch];
pthread_mutex_unlock(&rcin_mutex);
return v;
}
if (ch >= _rcin.channel_count) {
return 0;
pthread_mutex_unlock(&rcin_mutex);
return 0;
}
return _rcin.values[ch];
uint16_t v = _rcin.values[ch];
pthread_mutex_unlock(&rcin_mutex);
return v;
}
uint8_t PX4RCInput::read(uint16_t* periods, uint8_t len)
@ -87,8 +97,9 @@ void PX4RCInput::_timer_tick(void)
perf_begin(_perf_rcin);
bool rc_updated = false;
if (orb_check(_rc_sub, &rc_updated) == 0 && rc_updated) {
orb_copy(ORB_ID(input_rc), _rc_sub, &_rcin);
_last_input = _rcin.timestamp;
pthread_mutex_lock(&rcin_mutex);
orb_copy(ORB_ID(input_rc), _rc_sub, &_rcin);
pthread_mutex_unlock(&rcin_mutex);
}
// note, we rely on the vehicle code checking valid_channels()
// and a timeout for the last valid input to handle failsafe

4
libraries/AP_HAL_PX4/RCInput.h
View File

@ -5,6 +5,7 @@
#include <AP_HAL_PX4.h>
#include <drivers/drv_rc_input.h>
#include <systemlib/perf_counter.h>
#include <pthread.h>
class PX4::PX4RCInput : public AP_HAL::RCInput {
public:
@ -25,9 +26,10 @@ private:
struct rc_input_values _rcin;
int _rc_sub;
uint64_t _last_read;
uint64_t _last_input;
bool _override_valid;
perf_counter_t _perf_rcin;
pthread_mutex_t rcin_mutex;
};
#endif // __AP_HAL_PX4_RCINPUT_H__